偏颌畸形及其正颌手术对颞下颌关节的影响

<正>偏颌畸形(facialasymmetricdeformity)是颌骨畸形中比较常见的类型,包括先天性及发育性偏颌畸形,可分为偏侧小颌畸形及偏侧突颌畸形两类,多见于下颌骨,表现为面部左右不对称,上下中切牙的中线不一致,颏部及下颌中线偏向一侧,可有反或锁[1]。研究发现,偏颌畸形与颞下颌关节紊乱(temporomandibulardisorders,TMD)关系密切。TMD是颞下颌关节、咀嚼肌及周围相关结构表现的不同症状及体征的一个总称,临床表现主要包括关节区疼痛、关节杂音及功能障碍,伴或不伴有下颌骨运动受限、颞下颌关节(temporomandibularjoint,TMJ)及相关肌肉触痛等[2]。偏颌畸形严重影响患者的容貌、咀嚼和发音功能,随着正颌手术的顺利开展,正颌-正畸联合治疗不仅可以使偏颌患者恢复面容的正常和美观,而且可以使牙、、颌的形态和功能达到协调、美观和稳定,但正颌手术对其颞下颌关节的影响还在研究之中。     

上、下颌联合手术对髁突位置及其颞颌关节功能的影响

本文通过对16例上颌Le Fort Ⅰ型截骨,下颌体部截骨后,颞颌关节X光照片的测量,分析了髁状突的位置变化及其对颞颌关节功能的影响。结果发现在上颌前移下颌体部截骨后退后髁状突的位置移动较小,除个别病例外一般不伴有术后髁状突位置的移动及颞颌关节功能的改变.     

兔髁突软骨组织学分层的实验研究

目的：探讨髁突软骨的组织分层及其功能。方法：成年日本大耳白兔6只,处死后通过HE染色、免疫组化、原位杂交和透射电镜等方法进行软骨细胞PCNA、FGFR3、Ⅱ型胶原和蛋白多糖聚合体基因表达及超微结构等研究。结果：FGFR3在增殖层的浅层细胞中阴性表达,增殖层深层细胞开始为阴、阳性染色相间,逐渐变为全阳性染色细胞。PCNA在增殖层浅层细胞为阴、阳性染色相间,深层细胞均为阳性表达。增殖层的浅层细胞有蛋白多糖聚合体mRNA表达,但不表达Ⅱ型胶原mRNA。增殖层的深层细胞均强表达Ⅱ型胶原和蛋白多糖聚合体mRNA。电镜下见增殖层的深层细胞具有幼稚细胞和软骨细胞的双重表型。结论：髁突关节软骨应分为纤维层、增殖层、过渡层、软骨层和钙化软骨层5层,过渡层细胞可能属于前软骨干细胞。     

偏突颌患者颞下颌关节盘冠状向位置的MRI评估

目的研究偏突颌畸形患者双侧颞下颌关节盘-髁突位置在冠状位磁共振图像(magnetic resonance imaging,MRI)上的差异,并分析其关节盘移位程度与偏斜严重程度的相关性。方法对54例骨性Ⅲ类错患者进行标准化临床影像学检查得到闭口斜冠状位MRI,通过计算机软件测量分析其冠状位关节盘内外侧移位情况,应用wilcoxon秩和检验分析各组间颞下颌关节盘-髁位置在冠状位磁共振图像上的差异。结果40例偏突颌畸形患者中,偏斜侧7侧(17.5%)关节盘外侧移位,16侧(40.0%)内侧移位;而40侧偏斜对侧关节盘中,27侧(67.5%)关节盘内侧移位,仅2侧(5.0%)关节盘向外侧移位。14例(28侧)无偏斜骨性Ⅲ类患者中,18侧(64.3%)存在关节盘内侧移位,未发现外侧移位的关节盘。本研究证实了偏斜侧关节盘内外侧位置与偏斜对侧及无偏斜组存在显著性差异(P<0.05),中等到重度偏突颌患者偏斜侧关节盘位置与轻度及无偏斜者之间的差异具有统计学意义(P<0.05)。结论在冠状位磁共振图像中显示,中等到重度偏突颌患者偏斜侧关节盘倾向于向外侧移位,偏斜对侧关节盘倾向于向内侧移位。     

特发性髁突吸收及继发颌骨畸形的研究进展

特发性髁突吸收是一种发生于下颌骨髁突的进行性骨吸收疾病,因其病因病理不明及进行性发展的特点一直受到广泛的关注。患者主要临床表现包括下颌骨位置后缩、升支高度下降,前牙开、后牙早接触以及骨性Ⅱ类错等。本文就近年来特发性髁突吸收及继发颌骨畸形的病因病理、临床表现、治疗策略与方法等相关文章进行综述。     

骨性偏颌患者颞下颌关节的生物力学分析

目的:研究骨性偏颌患者牙尖交错位紧咬牙时颞下颌关节应力分布特征。方法:通过CT和MRI获得影像资料,使用Mimics、CADTIA和Ansysworkbench软件,建立包括颞骨、下颌骨和关节盘的有限元模型,计算咬合时颞下颌关节的应力分布。结果:关节盘和关节窝的主要受力在偏斜对侧分布偏内,偏斜侧分布偏外;偏斜对侧应力是一种集中的方式,偏斜侧是一种分散的方式。结论:偏颌患者偏斜侧关节盘可能倾向于向外侧移位,偏斜对侧关节盘可能倾向于向内侧移位。     

两种异常咬合刺激对小鼠髁突影像及组织形态学影响研究

目的 探究异常咬合刺激对小鼠髁突影像及组织形态学影响.方法 选取6周龄雌性C57BL/6J小鼠36只,根据饲养时间(3、7周)均分小鼠后,再随机分为对照组、单侧前牙反(unilateral anterior crossbite,UAC)组和双侧前牙咬合抬高(bilateral anterior elevation,B...     

大鼠髁突软骨增殖细胞核抗原表达的昼夜节律

目的：了解髁突软骨细胞增殖的昼夜节律性,为探讨一天中临床功能矫形治疗介入的最佳时段提供初步实验依据。方法：应用免疫组织化学方法对生长期大鼠髁突软骨细胞增殖细胞核抗原（PCNA）表达进行检测分析,结果：大鼠髁突软骨细胞的PCNA表达,存在明显的昼夜节律性,其峰值相位约在12：00,谷值相位约在0：00。结论：髁突软骨细胞增殖存在昼夜差异性,其高峰期在白天,功能矫治一天中,可能存在最佳时段。     

髁突复位钢板在下颌升支矢状劈开术中的应用

为了防止正颌外科术后髁突位置变化引起颞下颌关节症状及畸形复发，作者对１７例颌骨畸形患者行下颌升支矢状劈开截骨术中，应用髁突复位钢板记录和恢复髁突术前位置。结果提示，１５例患者的３０侧髁突位置术后检查未发生移位，仅２例患者各有１侧髁突发生了内侧旋转移位。作者认为，髁突复位钢板对于记录和恢复髁突术前位置是行之有效的。     

Semi-automated three-dimensional volumetric evaluation of mandibular condyles

Objectives

The aim of this study is to research the mandibular condyle volumes of the Turkish subpopulation by sex, age, laterality, and posterior occlusal support, to provide volumetric data for young and old patient groups.

Methods

The CBCT images of 690 condyles from 345 patients (165 females and 180 males) were assessed. Patients aged 18–25 years were chosen for the younger group, and 45–70 years for the older group. The dental statuses of the older patient group were divided into three categories, based on the Eichner index. All the CBCT images were transferred to the three-dimensional volumetric analysis software, ITK-Snap (Penn Image Computing and Science Laboratory (PICSL) at the University of Pennsylvania and Scientific Computing and Imaging Institute (SCI) at the University of Utah) and analyzed with sagittal, coronal, and axial sections. Mandibular condyles were defined using semi-automatic segmentation, then manual segmentation was performed to ensure accuracy. Analyses were performed using MedCalc statistical software. The p value <?0.05 was considered statistically significant.

Results

The mean right condyle volume for the whole sample (n?=?345) was 1678.8 mm³ and the left condyle volume was 1661.3 mm³. Males had a larger condyle volume than females in both the younger and older patient groups (p?=?0.035, p?<?0.01, respectively). The Eichner index did not correlate significantly with condylar volume in the older patient group (p?=?0.134, p?=?0.122).

Conclusion

There were significant differences between the volumes of mandibular condyles for different sex, while there were no significant differences in relation to age, laterality, and posterior occlusal support.

     

Response of mandibular condyles of juvenile and adult rats to abnormal occlusion and subsequent exemption

ObjectiveThe adaptation capacities of the mandibular condyle in response to mechanical stimuli might be different between juveniles and adults, but has not been compared. This study aimed to investigate whether abnormal molar occlusion and subsequent molar extraction could lead to different remodeling responses in the mandibular condyles of juvenile and adult rats.MethodsAbnormal molar occlusion (AMO) was established in the 5- and 16-wk old rats by moving their maxillary left and mandibular right third molars distally. AMO was removed in the molar extraction group at 4 weeks but remained in the AMO group. All rats were sacrificed at 8 weeks. Micro-computed tomography, histomorphology, immunohistochemistry and real-time PCR were adopted to evaluate the remodeling of condylar subchondral bone.ResultsCondylar subchondral bone loss and increased osteoclastic activities were observed in both juvenile and adult AMO groups, while increased osteoblastic activities were only seen in the juvenile AMO group. Decreased bone mineral density, bone volume fraction and trabecular thickness, but increased trabecular separation, number and surface of osteoclasts and mRNA levels of TRAP, cathepsin-K, RANKL in the juvenile AMO group were all reversed after molar extraction (all P < 0.05). However, these parameters showed no difference between adult AMO and extraction groups (all P > 0.05).ConclusionsAbnormal molar occlusion led to degenerative remodeling in the mandibular condyles of both juvenile and adult rats, while exemption of abnormal occlusion caused significant rescue of the degenerative changes only in the juvenile rats.     

Ultrastructure of hypertrophic chondrocytes of rat mandibular condyles using lanthanum-containing fixatives

The effect of lanthanum on hypertrophic chondrocytes of rat mandibular condyles during fixation was investigated by electron microscopy. Lanthanum induced a structural modification resulting in the absence of the lacunar space, particularly in the premineralizing hypertrophic zone. Lanthanum-glutaraldehyde fixation demonstrated metallic deposition at the territorial matrix, some extracellular granules and on the cell membrane. The lanthanumprecipitated extrachondrocytic granules became more abundant towards the mineralization front. Pretreatment with EGTA abolished these granules, suggesting that they may represent extracellular calcium-binding sites.     

Odontometric evaluation of mandibular premolars with tooth shape deviation

Abstract Objective: To evaluate the mean dimensions and morphologic characteristics of mandibular premolars that had mesiodistally elongated and faciolingually squeezed tooth shape deviations (MnP-TSD) and determine the population prevalence of this anomaly. Materials and Methods: Clinical photographs and study models were made for all new patients with MnP-TSD teeth who were seen over 20?years. The mesiodistal (MD) and faciolingual (FL) dimensions of the anomalous premolars were measured. MD/FL indices and MD × FL mm(2) occlusal crown areas were calculated and means and standard deviations were derived. Male and female means from the mandibular first and second anomalous premolars (MnP1/MnP2-TSD) were statistically compared against gender-specific means derived from published normative data using Student's t-tests and chi-square tests. Results: Fifty-six individuals (33 male and 23 female) with MnP-TSD were identified, giving a male to female ratio of 1.4∶1, while the prevalence rate in the indigenous British population was estimated to be 0.6%. The MD widths of the MnP1-TSD and MnP2-TSD teeth were approximately 1?mm wider than normal, while the FL diameters were about 0.5?mm and 1.5?mm narrower respectively, for the first and second premolar teeth. The MD/FL indices, instead of being under 90 as usual were above 100, while the mean MD/FL mm(2) crown surface areas were normal. Conclusions: This study supplies odontometric dimensional and morphologic data on MnP-TSD teeth that provide a reference source for future comparisons.     

Comparative evaluation of the mandibular distraction zone using ultrasonography and conventional radiography

The purpose of this study was to determine the efficacy of ultrasonography (USG) for the evaluation of bone formation in the mandibular distraction wound and to compare this with radiographic evaluation, which is currently the standard modality. Twenty-two patients underwent mandibular distraction (30 sides) with a variety of distraction devices. The wounds were assessed with plain radiographs and USG at established time intervals. Estimates of bone formation using a semiquantitative bone fill score were made for radiographs and USG. USG bone fill scores were correlated with radiography scores. At week 4 the difference between the scores was statistically significant (P = 0.01); at all other time points, USG and radiography scores were comparable. At week 4, USG scores were significantly higher than the corresponding radiography scores, indicating that USG is an earlier indicator of calcification in the distraction zone as compared to radiography. USG evaluation of the distraction osteogenesis (DO) zone has many inherent advantages over conventional methods. The results of this study indicate that USG is an accurate non-invasive technique that may prove to be useful in assessing the mandibular DO regenerate in patients.     

Vivosorb, Bio-Gide, and Gore-Tex as barrier membranes in rat mandibular defects: an evaluation by microradiography and micro-CT

Objectives: The objectives of this study were to determine whether a new degradable synthetic barrier membrane (Vivosorb^®) composed of poly(dl ‐lactide‐?‐caprolactone) (PDLLCL) can be useful in implant dentistry and to compare it with collagen and expanded polytetrafluoroethylene (ePTFE) membranes. Material and methods: In 192 male Sprague–Dawley rats, a standardized 5 mm circular defect was created through the right angle of the mandible. New bone formation was evaluated by post‐mortem microradiography and micro‐CT (μCT) imaging. Four groups (control, PDLLCL, collagen, ePTFE) were evaluated at three time intervals (2, 4, and 12 weeks). In the membrane groups the defects were covered; in the control group the defects were left uncovered. Data were analysed using a multiple regression model. Results: New bone formation could be detected by post‐mortem microradiography in 130 samples and by μCT imaging in 112 samples. Bone formation was progressive in 12 weeks, when the mandibular defect was covered with a membrane. Overall, more bone formation was observed underneath the collagen and ePTFE membranes than the PDLLCL membranes. Conclusions: In contrast to uncovered mandibular defects, substantial bone healing was observed in defects covered with a PDLLCL membrane. However, bone formation in PDLLCL‐covered defects tended to be less than in the defects covered with collagen or ePTFE. The high variation in the PDLLCL samples at 12 weeks may be caused by the moderate adherence of this membrane to bone compared with collagen. These results indicate that further study is needed to optimize the properties of PDLLCL membranes.     

The effects of mandibular retractive force on the growing rat mandible

The purpose of this study was to investigate the three-dimensional effects of a mandibular retractive force on the growing rat mandible and mandibular growth after the force was removed. Eighty 4-week-old male Wistar rats served as experimental animals and 100 4-week-old male Wistar rats served as the control group. The experimental rats were divided into four groups. Thirty grams of retractive force was applied to each mandible for 4 weeks. Each group was then killed after 4-, 8-, 10-, 12-, or 16-week periods. At the time of death, tibia, skull, and mandible were removed, measurements of those bone specimens were taken, and histologic examinations were performed. Compared with the control group, the experimental group demonstrated no significant differences in body weight nor in the length of measurements of the tibia, skull, and proximal end of the tibia. The mandibles of the experimental group demonstrated shorter anteroposterior length, higher coronoid processes, and a thicker corpus in the retromolar region and condylar neck. The condylar cartilages of the experimental group showed moderate adaptation in the histologic sections. However, mandibles of the experimental animals did not show any catch-up growth behavior after removal of the force. It was concluded that the mandibular retractive force could produce overall growth retardation and transformation of growing rat mandibles, but the force had no effect on the growth behavior after the appliance was removed.     

基于micro-CT的下颌牙龈癌颌骨侵犯的影像学评估及分析

目的： 对下颌牙龈癌颌骨侵犯进行影像学评估及分析,为进一步优化手术方案及术后治疗提供影像学依据。方法： 选择60例下颌牙龈癌手术患者,分析术前曲面体层片、平扫和增强CT,并对其中符合条件的30例手术标本进行micro-CT三维重建,分析骨密度、骨小梁厚度、骨小梁分离度等相关参数。采用SPSS 22.0软件包对数据进行统计学分析。结果： 常规影像学检查,曲面体层片、平扫及增强CT均有不足,micro-CT三维重建可以准确区分骨松质及骨皮质,评估下颌骨侵犯的范围及程度,相应的数据参数分析癌边缘及癌中心与正常下颌骨组织的皮质骨骨密度显著降低（P<0.05）,骨小梁厚度显著变薄（P<0.05）,松质骨骨密度显著降低（P<0.05）。癌中心与正常下颌骨组织骨小梁分离度增加（P<0.05）。结论： 目前对于下颌牙龈癌的手术方案还存在争议,进一步提高CT检查精度,可能会为制定下颌牙龈癌手术方案提供更精确的指导。